Dual actuation safety belt buckle mechanism

ABSTRACT

A mechanical conversion system provides push-button actuation of a slide-action locking mechanism, while preserving the possibility of actuation by sliding handle movement where this is desired.

United States Patent m1 Carter 1 51 Apr. 24, 1973 DUAL ACTUATION SAFETY BELT [56] References Cited BUCKLE MECHANISM UNITED STATES PATENTS [75] Inventor: Andrew G. Carter, Grand Rapids,

Mich 3,153,270 10/1964 Linblad ..24/23O A V 3,156,025 1 1/1964 Carter et al... .....24/230 A [73] Assignee: Carter Engineering Company, 3,227,992 1/1966 Strong ..248/27 Grand Rapids, Mich. 3,505,71 l 4/1970 Carter ..24/230 AK 3,523,340 8/1970 Stoffel ..24/23O AK [22] Flledl July 22, 1971 3,644,967 2/1972 Romanzi ..24 230 AK App]. No.: 165,160

U.S. Cl. ..24/230 A, 24/230 AP, 24/230 AK,

. 297/384 Int. Cl. ..A44b 19/00, A47C 31/00 Field of Search ..24/23O AP, 230 AK,

Primary ExaminerPaul R. Gilliam Att0rneyGlenn B. Morse ABSTRACT A mechanical conversion system provides push-button actuation of a slide-action locking mechanism, while preserving the'possibility of actuation by sliding handle movement where this is desired.

12 Claims, 29 Drawing Figures Patentd April 24, 1973 9 Sheets-Sheet 5 Andrew G. Carter BY zw M ATTORNEY Patented April 24, 1973 3,728,764

9 Sheets-Sheet 4 'IIIIIIIIII Fig. 9 8 5 as as fee I 85 i I as =5" Fig. ll i l 7 llvVElvrol? 5 'Andrew 6. Carter 3 a7 Fig. /0 444% ATTORNEY Patented April 24, 1973 9 Sheets-Sheet 5 INVENTOR V! E m M .1. 0 w H 6 W e r d n A .V! B 4 I .a H

Patented April 24, 19 73 9 Sheets-Sheet 6 I I -I //VVEN7'0/? Andrew G. Carter BY g 44m ATTORNEY Patented April 24, 1973 9 Sheets-Sheet 7 Fig. 18

Fig. I9

I00 Fig. 2/

ATTORNEY Fig. 20

Patented April 24, 1973 9 Sheets-Sheet 8 l/Vl/E/VTOR Andrew G. Carter A TTOR/VEY Patented April 2 4, 1973 9 Sheets-Sheet 9 Fig. 25

Fig 29 V INVENTOR I I7 Fig. 27

A TTORNEY DUAL ACTUATION SAFETY BELT BUCKLE MECHANISM BACKGROUND OF THE INVENTION ponents of the locking mechanism; and in the other,

belt tension forces are resisted by lateral interengagement of fixed abutments on the buckle sections. By far the majority of buckle mechanisms currently available on the market are the first type. An example of the latter arrangement is described .in the Andrew G. Carter U.S. Pat. No. 2,904,866. Where the belt forces are transmitted through movable components of the locking mechanism, it appears that the designer has somewhat more freedom in the arrangement and configuration of the mechanism. The disadvantage of this type of mechanism, however,'is in the strength requirements of the movable components, and the fact that it becomes more difficult to unlock the device under conditions of substantial belt tension. These occur in cases where it becomes necessary to remove a crash victim from a damaged car, or where the user of the belt might have enough of an injury to interfere with his ability to unlock the buckle. Where the buckle sections are interengaged laterally against fixed surfaces, the locking mechanism need only maintain the lateral interengagement. Forces required for this purpose are but a small fraction of those involved in the transmission of belt tension. The attitude of interengaged surfaces can be established at a predetermined angle with respect to the axis of belt tension such that the forces are held down to just that which will assure separation of the buckle sections upon release of the locking mechanism. In spite of the advantages, the fixed-abutment form of buckle mechanism has not been exploited to anywhere near the extent of the stressed locking mechanism.

Several forms of actuation have been developed for unlocking a buckle mechanism, and each of these has significant advantages and disadvantages. Lever-action mechanism has been used in conjunction with both types of locking system, and this arrangement usually provides a very simple series of problems in mechanical design. The disadvantage of the lever, however, is that it is easily possible for the mechanism to be unlocked by the effect of inertia tending to'swing the lever forward under crash conditions. This form of actuation is also somewhat vulnerable to accidental release by snagging clothing against the lever. The type of actuation most free of problems of inertia is the slide action, in which movement of a handle in a direction of belt tension will effectuate release of the mechanism. Since the buckle is normally placed on the lap, or in the frontal area of the user, the most predominant inertia will have practically no tendency to move the handle sideways to produce accidental release. This form of actuation lends itself extremely well to the operation of the fixed-abutment locking mechanism described previously. A third type of actuation, and one which has seen significant development within the recent past, centers in the use of a push button adapted to unlock the mechanism in response to relatively small forces applied at a relatively small area. This area can be protected by surrounding structure to a degree that accidental actuation is highly improbable. The general use of push buttons in controlling mechanism of all sorts has become so familiar to the average person that recent safety specifications issued by a governmental agency has had the effect of standardizing on safety belt buckle actuation of this type. A difficulty with this form of mechanism, however, is in the fact that relatively small forces are available for operation of the un-,

locking function, which has tended to restrict the use of this type of actuation to the type of mechanism in which the components have a pivotal movement. As a result, the push button has become generally associated with the type of buckle mechanism in which the locking components carry the stresses resulting from belt tension. Because of the limited travel of the push button, and the limited forces that can be comfortably applied against it, the problem of unlocking a push button mechanism under residual belt tension is very difficult to cope with. A great disadvantage of the push button action, which is a matter of record, occurs when a wearer inadvertently fastens the buckle in upside-down position, so that the push button is against his body. There is no way in which the buckle can be released under stress in this position, except with great confusion and difficulty. The buckle must be turned over so that the push button is on the outside before it can be opened by the wearer. This is not true of the slide action, which will permit instant release, even if fastened with the push button next to the body of the wearer. It may also be noted in passing that there appears to be no previous development of a push button mechanism which would retain another important feature of the slide action device, which is the possibility of utilizing the movement of the handle to effectuate release of the belt for initial tension adjustment. The present invention has been developed to provide the structural advantages associated with the fixed-abutment type of locking mechanism, and also those associated with slide-action actuation, in conjunction with the use of a push button to unlock the device in the interests of conformity with the current emphasis on standardization. An outstanding advantage of this present design is that it provides both types of releases.

SUMMARY OF THE INVENTION A mechanical force-conversion system changes the force applied to a push button into a transverse force parallel to the axis of belt tension to create release of the locking mechanism by inducing movement of a locking slide. This slide is movable from a position in which its presence maintains the lateral interengagement of the buckle sections, to a position in which the two sections are free to separate. In the preferred form of the invention, the push button is supported primarily by a cam surface on a slide member, with reactions in the direction of belt tension being generated by the interengagement of the push button with a guideway in the handle of the buckle. A toggle mechanism for converting the direction and magnitude of push button force is also provided as an alternate form of the invention. It is preferable that the invention be incorporated in a buckle mechanism in which the handle is capable of sliding movement to a degree to which it can intercept the locking slide on movement in one direction (in addition to actuation by the push button), and sliding movement in the opposite direction to effectuate belt release. This arrangement provides an assembly in which the components are largely located by the interaction of adjacent moving parts, which results in a 1 very effective and economical assembly'operation.

DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of the section ofa buckle mechanism containing the active components of the present invention.

FIG. 2 is a side elevation of the buckle section shown in FIG. 1.

FIG. 3 is a section on the plane 3-3 of FIG. 2. FIG. 4 is a section on the plane 4-4 of FIG. 3, with the buckle illustrated in the normal condition.

FIG. 5 is a view similar to FIG. 4, with the mechanism in the actuated condition corresponding to release of the buckle sections.

FIG. 6 illustrates a position of the mechanism corresponding to release of the jamming action of the belttension adjustment.

FIG. 7 is an exploded view showing the components of the device illustrated in FIGS. 1 through 6.

FIG. 8 is a section corresponding to that of FIG. 4, illustrating a modified form of the invention with respect to the configuration of the slide member.

FIG. 9 is a view of the mechanism illustrated in FIG. 8 in the actuated condition. I a

FIG. 10 is a plan view of the slide member used in the FIG. 8 mechanism.

FIG. 11 is a side elevation of the slide member shown in FIG. 10.

FIG. 12 is a perspective view of the slide members shown in FIGS. 10 and 11.

FIG. 13 is a perspective view of the frame member of the mechanism illustrated in FIG. 8.

FIG. 14 is a perspective view showing the assembled relationship of theslide member and frame shown in FIGS. 12 and 13.

FIG. 15 is a section in plan of the mechanism shown in FIG. 8, with the upper portion of that handle and the push button removed.

FIG. 16 is a section on the plane 16-16 of FIG. 15.

FIG. 17 is a side elevation of the belt-end retention 1 clip shown in FIG. 15.

FIG. 18 is a sectional elevation through the central portion of a buckle mechanism of a modified form of the invention, in which the slide member is actuated by a toggle linkage.

FIG. 19 is a view of the mechanism shown in FIG. 18, in the actuated condition.

FIG. 20 is a plan view of slide member associated with the FIG. 18 mechanism.

FIG. 21 is a side elevation ofthe slide member shown in FIG. 20.

FIG. 22 is a perspective view of the slide member shown in FIGS. 20'and 21. l

FIG. 23 is a perspective view of the frame used in the FIG. 18 assembly.

FIG. 24 is an' exploded view showing the components associated with the FIG. 18 mechanism.

FIG. 25 is a section in plan showing a modified form of belt terminal bar.

FIG. 26 is a section on the plane 26-26 of FIG. 25.

FIG. 27 is a view of a further modification in the structure of the belt terminal bar. 1

FIG. 28 is a section on the plane 28-28 of FIG. 27. FIG. 29 is a side elevation of the arrangement shown in FIG. 27.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to FIGS. 1 through 7, the buckle section illustrated in FIG. 1 includes the channel-shaped frame I 30 surrounded on the top, bottom, and sides by the handle assembly 31. This handle is slideably mounted on the frame 30, and includes the upper section 31a and the lower section 31b united at the opposite offset junctions 32 and 33. The sections 31a and 31b can be held together by heat fusion, adhesive, or by clips as shown at 34 and 35 arranged at corresponding positions on the opposite side of the assembly. These clips hook into appropriate recesses in the material of the handle sections 31a and 31b, which are preferably of a convenient die-molded plastic. Both sides of the handle assembly are preferably serrated, as indicated at 36, to provide a convenient hand-gripping surface for controlling the sliding movement of the buckle. The top portion of the handle section 31a is formed in the configuration of a truncated pyramid, with a central opening 37 receiving the push button 38. The pyramid configuration provides protection for the push button, preventing accidental actuation, and also providing a depth dimension permitting portions of the handle section 310 to function as a guideway for the sliding movement of the button as it is actuated. This guideway function is provided by the tubular inward extension 39, which is integral with the top handle section 31a. A shoulder 40 coacts with the opposite shoulder 41 on the push button 38 to limit the outward movement of the button, and retain it in assembled relationship.

The buckle section illustrated in FIG. I cooperates with the tongue plate 42, which is connected to a length of belt (not shown) to form a second section of the assembly. Referring to FIG. 7, this plate 42 has apertures 43 and 44 providing surfaces 45 and 46, respectively, for interengagement with the faces 47 and 48 of the protrusions 49 and 50 formed in the base of the frame 30. The configuration of the apertures 43 and 44 is such as to receive the protrusions 49 and 50, with the tongue plate 42 lying flat against the top surface 51 of the base of the frame 30. The interengagement of projection 49 and 50 with the apertures 43 and 44 becomes the disengageable point of transfer of forces resulting from belt tension. One section of belt is interengaged with the slot 52 in the tongue plate 42, and another section of belt 53 is interengaged with the terminal bar 54. The transfer of belt tension forces is maintained as long as the tongue plate 42 is held down close to the surface 51 of the mechanism frame, and this holding function is performed by the slide member 55. The edge portions 56 of the slide member are received in the slots 57 and 58 in the flanges 59 and 60 of the frame (refer to FIG. 7), with the slide member free to move from the locking position shown in FIG. 4 to the release position shown in FIG. 5. A leaf spring 61 bearing against a bar 62 biases the slide member 55 to the left, as shown in FIGS. 4 and 5, tending to maintain the locking position of the assembly. The bar 62 has end extensions 63 and 64 received in the slots 65 and 66 to maintain the position of the bar, with the short flanges 67 and 68 of the bar being disposed above and below the leaf spring 61 to maintain the position of the spring against displacement in a direction perpendicular to the surface 51 of the frame. A hold-down hook 69 is preferably formed integrally from the material of the frame 30, and prevents excessive upward deflection of the slide member 55, as long as the slide member is in the locking position shown in FIG. 4. The tongue plate 42 is cut away at 70 to provide clearance for the hook 69. The locking mechanism thus far described is shown in the Andrew G. Carter US. Pat. No. 3,505,71 l. The retaining clip 71 is optional, and merely controls the free end 72 of the belt 53. Sliding movement of the handle 31 to the right will bring the portion 73 of the handle into engagement with the portion 74 of the slide member to move it from locking to release position. This operation is associated with the conventional slide-action buckle mechanism, with the handle moving with respect to the frame 30. I

Operation of the locking mechanism through actuation of the push button 38 is possible through the interengagement of the inclined cam surface 74 on the push button 38, and 75 on the ramp portion of the slide 55. Downward movement of the push button is limited by the interengagement of the bottom surface 77 on the push button with the top surface 78 of the slide 55, and also by the interengagement of the upper edge 79 with the surface 80 on the push button (refer to FIG. 4). Referring to FIG. 5, the fully actuated position of the push button 38 is thus supported by the slide member. The lateral forces necessary to move the slide 55 to the release position shown on FIG. 5 against the action of the spring 61 are provided by the interengagement of the button with the side walls of the guideway 39 of the handle. It should be noted that the interengagement of the slide with the surfaces 77 and 80, which are spaced along the length of the assembly, tends to stabilize the push button against clockwise rotation (as viewed in FIGS. 4 and 5) under the actuating forces. Any tendency for the button to tip will ultimately be corrected by the final position of the button, as it appears in FIG. 5.

The buckle assembly preferably has a characteristic shown in the Carter US. Pat. No. 3,505,711, in which sliding movement of the handle 31 to the left, as viewed in FIGS. 4 through 6, will produce a release of the jamming action of the terminal bar 54 by moving it away from the humpv 81 formed in the base 30. The ends of the bar 54 extend through the opposite openings 82 and 83 (refer to FIG. 7) in the flanges S9 and 60, respectively, where they are received in appropriate recesses as shown at 92 (in FIG. 16) in the handle 31. This interengagement of the handle with the terminal bar 54 provides a resistance to sliding movement of the handle to the left with respect to the frame 30, as viewed in FIGS. 4 through 6, to establish the necessary reaction forces resulting from the actuation of the push button 38. Limitation of the movement of the handle to the right is provided by the interaction of the portion 73 of the handle with the slide member, and a consequent limitation of the movement of the slide member by the length of the slots 57 and 58.

A significant safety feature is incorporated in the otherwise conventional belt-terminal adjustment system centering in the bar 54. This bar is preferably made of a material which will significantly reduce in its bending strength under relatively low temperatures. A, polycarbonate material commonly referred to by the trademark as Lexan" has the characteristic of softening significantly at temperatures on the order of 275 Fahrenheit. In cases where a fire has developed in a crashed vehicle, the sudden generation of high temperatures will automatically cause any residual belt tension to immediately pull the weakenedbar 54 out of the assembly and release the occupant without the necessity of unlocking the mechanism.

The modification shown in FIGS. 8 through 15 is similar to that previously described, with the exception of the configuration of the locking slide and the corresponding modification of the length of the slots in the frame which function as the guideway for the slide. The slide 85 has the support portions 86 and 87 extending further to the right, as viewed in FIG. 8, than the supporting portions 56 of the slide 55. The slots 88 and 89 in the flanges 90 and 91, respectively, are of greater length to accomodate this difference in the slide. This configuration may be used when it appears to be desirable to do so in order to prevent a binding action of the slide within the guide slots 88 and 89 by carrying the support point more directly underneath the point of application of forces by the push button 90. Placement of the support in this position during the actuation of the button will have a reduced tendency to rotate the slide against the upper and lower walls of the slots 88 and 89 (refer to FIG. 13). Any such tendency to rotate the slide will tend to generate a binding action between the slide and the upper and lower walls of the guide slots 88 and 89. Whether or not this extension becomes necessary will be determined largely by the coefficients of friction between the push button and the slide, between the push button and the guideway portion of the handle, and by the smoothness and coefficient of friction of the walls of the slots 88 and 89 and the portions 86 and 87 of the slide. The effect of wear must be considered here, which has a tendency to roughen the surfaces and make ordinary coefficients of friction somewhat meaningless. In the mechanism shown in FIG. 8, and also that shown in FIG. 4, it should be noted that the sufficient clearance should exist between the bar 62 and the push button to permit slight movement of the handle 31 to the left with respect to the frame to permit the edge 91 of the recesses 92 in the opposite sides of the handle 31 to move the terminal bar 54 to the release condition illustrated in FIG. 6. This movement is relatively small, but must be kept in mind if the push button design (in the un-actuated positions whown in FIGS. 4 and 8) extends downward far enough to interfere with significant movement of the handle. The extension 93 of the handle recesses, incidentally, is provided for clearance to avoid interference with the portions 56 of the slide 55, and the portions 86 and 87 of the slide 85. The locking mechanism shown in FIGS. 8 and 9 is otherwise identical to the mechanism described in' connection with FIGS. 4 and 5. The assembly of the parts becomes a very, simple matter, in view of the fact that the components are relatively selfpositioning. After the slide has been interengaged with the guideway slots in the frame, the bar 62 can be slipped into place, followed by the insertion of the spring 61. As with the assembly of the slide, the belt terminal bar can be inserted from the diagonal position to engage its slots in the frame flanges, after which the sections 310 and 31b of the handle are simply placed together over the assembly, with the push button previously assembled to the handle section 31a. The handle sections are then joined by heat fusion, adhesive, or by the clips previously described.

The modification illustrated in FIGS. 18 through 24 utilizes a different system for converting the push button force into a force in the direction of the axis of belt tension for the purpose of withdrawing the slide to release position. A toggle mechanism is based upon the link 94, which is pivotally connected to the push button 95 by the pin 96, and also pivotally connected to the locking slide 97 by the pin 98. The pin 98 extends through the bearing holes formed in the ears 99 and 100 integral with the slide 97, with the link 94 being received between these cars. The pin 96 traverses appropriate holes 101 in the side walls of the push button 95 defining the opposite sides of a recess 102 in the underside of the push button 95. The initial (unactuated) relationship of the position of the pins 96 and 98, as shown in FIG. 18, should produce enough incline to the movement of the push button to produce a component to the right of sufficient magnitude to overcome the coefficient of friction between the slide and the slots 103 and 104 in the side flanges of the frame 105, which form a guideway for the movement of the locking slide 97 (refer to FIG. 23). In the fully actuated position of the toggle mechanism shown in FIG. 19, the push but-' ton 95 should never reach a position in which it is completely drawn downwardly out of engagement with the tubular guideway 106 formed in the handle 107. Except for this difference in the arrangement for converting the magnitude and direction of the push button force into a force for inducing movement of thelocking slide, the buckle assembly shown in FIGS. 18 through 24 is similar to that described previously.

FIGS. 25 through 29 illustrate modifications in the design of the adjustable belt terminal. In FIGS. 25 and 26, the movable terminal bar 108 generates a binding action against the belt 109, with the fixed bar 110 replacing the hump 81 of the assembly previously described. In the arrangements shown in FIGS. 25 and 26, the lower section of the belt 111 carries the primary belt tension, with the free end 109 being'available on top for increased accessibility. ln FIGS. 27 through 29, an arrangement is shown in which the release of the belt terminal is effectuated by a control independent of the position of the handle 112. The tubular terminal bar 113 is provided with end inserts 114 and 115 that extend through the openings 116 and 117 in the frame and .handle (on both sides of the assembly) so that manual force can be applied to move the bar 113 to release the jamming pressure. The openings 117 in the handle must be of sufficient length to accomodate the sliding movement of the handle normally utilized to produce unlocking, if the slide action is to be used in addition to thepush button actuation.

Iclaim:

1. A safety belt buckle including a tongue plate adapted to receive a first belt section; a frame; a belt bar movably mounted in said frame between jamming and releasing positions, and adapted to receive and adjustably secure a second belt section; laterally interengageable means on said frame and plate adapted to transfer belt tension forces when said frame and plate means are interengaged; a slide member mounted in said frame for movement in a. directionsubstantially parallel to the axis of belt tension established by the position of said plate and belt bar with'said frame and plate means are interengaged, said slide memberbeing movable from locking position maintaining the engagement of said frame and plate means to a position reIeas-- ing said frame and plate means for lateral separation; biasing means urging said slide member to locking position; and handle means slideably mounted on said frame for movement in a direction parallel to said axis, said handle having means disposed to intercept said belt bar on movement of said handle in a direction to move said belt bar to release position, wherein the improvement comprises:

a push button mounted in said handle for movement transverse to the direction of sliding movement of said handle;

means on said slide member forming an inclined cam surface with respect to-the direction of movement of said push button, said push button having a portion disposed to engage said cam surface an application of exterior pushing force against said push button, said inclined cam surface being oriented to induce movement of said slide member to release position on actuation of said push button; and

means providing resistance of said handle to sliding movement with respect to said frame, said resistance being ofa magnitude in excess of the force required to move said slide member to release position.

2. A buckle as defined in claim 1, wherein said push button and slide member have interengageable abutment surfaces limiting the travel of said push button.

3. A buckle as defined in claim 2, wherein said abutment surfaces include the end portion of said slide member means forming an inclined cam surface.

4. A buckle as defined in claim 1, wherein said handle has means forming a guideway for the movement of said push button, said push button having a cantilever extension constituting said portion thereof disposed to engage said slide member cam surface.

5. A safety belt buckle including a tongue plate adapted to receive a first belt section; a frame;'a belt bar movably mounted in said frame between jamming and releasing positions, and adapted toreceive and'adjustably secure a second belt section; laterally interengageable means on said frame and plate adapted to transfer belt tension forces when said frame and plate means are interengaged; a slide member mounted in said frame for movement in a direction substantially parallel to the axis of belt tension established by the position of said plate and belt bar with said frame and plate means are interengaged, said slide member being 7 movable from locking position maintaining the engagetion disposed to engage said cam surface on application of exterior pushing force against said push button, said inclined cam surface being oriented to induce movement of said slide member to release position on actuation of said push button.

6. A buckle as defined in claim 5, wherein said push button and slide member have interengageable abutment surfaces limiting the travel of said push button.

7. A buckle as defined in claim 6, wherein said abutment surfaces include the end portion of said slide member means forming an inclined cam surface.

8. A buckle as defined in claim 5, wherein said handle has means forming a guideway for the movement of said push button, said push button having a cantilever extension constituting said portion thereof disposed to engage said slide member cam surface.

9. A safety belt buckle including a tongue plate adapted to receive a first belt section; a frame; a belt bar movably mounted in said frame between jamming and releasing positions, and adapted to receive and adjustably secure a second belt section; laterally interengageable means on said frame and plate adapted to transfer belt tension forces when said frame and plate means are interengaged; a slide member mounted in said frame for movement in a direction substantially parallel to the axis of belt tension established by the position of said plate and belt bar with said frame and plate means are interengaged, said slide member being movable from locking position maintaining the engagement of said'frame and plate means to a position releasing said frame and plate means for lateral separation; biasing means urging said slide member to locking position; and handle means slideably mounted on said frame for movement in a direction parallel to said axis, said handle having means disposed to intercept said belt bar on movement of said handle in a direction to move said belt bar to release position, said handle also having means disposed to intercept said slide member to induce movement thereof to release position, said latter movement being in the opposite direction to that required to move said belt bar to release position, wherein the improvement comprises:

a bush button mounted in said handle for movement transverse to the direction of sliding movement of i said handle;

means on said slide member forming an inclined cam surface with respect to the direction of movement of said push button, said push button having a portion disposed to engage said cam surface on'application of exterior pushing force against said push button, said inclined cam surface being oriented to induce movement of said slide member to release position on actuation of said push button; and

means providing resistance of said handle to sliding movement with respect to said frame, said resistance being ofa magnitude in excess of the force required to move said slide member to release position.

10. A buckle as defined in claim 9, wherein said push button and slide member have interengageable abutment surfaces limiting the travel of said push button.

11. A buckle as defined in claim 10, wherein said abutment surfaces include the end portion of said slide member means forming an inclined cam surface.

12. A buckle as defined in claim 9, wherein said handle has means forming a guideway for the movement of said push button, said push button having a cantilever extension constituting said portion thereof disposed to engage said slide member cam surface. 

1. A safety belt buckle including a tongue plate adapted to receive a first belt section; a frame; a belt bar movably mounted in said frame between jamming and releasing positions, and adapted to receive and adjustably secure a second belt section; laterally interengageable means on said frame and plate adapted to transfer belt tension forces when said frame and plate means are interengaged; a slide member mounted in said frame for movement in a direction substantially parallel to the axis of belt tension established by the position of said plate and belt bar with said frame and plate means are interengaged, said slide member being movable from locking position maintaining the engagement of said frame and plate means to a position releasing said frame and plate means for lateral separation; biasing means urging said slide member to locking position; and handle means slideably mounted on said frame for movement in a direction parallel to said axis, said handle having means disposed to intercept said belt bar on movement of said handle in a direction to move said belt bar to release position, wherein the improvement comprises: a push button mounted in said handle for movement transverse to the direction of sliding movement of said handle; means on said slide member forming an inclined cam surface with respect to the direction of movement of said push button, said push button having a portion disposed to engage said cam surface on application of exterior pushing force against said push button, said inclined cam surface being oriented to induce movement of said slide member to release position on actuation of said push button; and means providing resistance of said handle to sliding movement with respect to said frame, said resistance being of a magnitude in excess of the force required to move said slide member to release position.
 2. A buckle as defined in claim 1, wherein said push button and slide member have interengageable abutment surfaces limiting the travel of said push button.
 3. A buckle as defined in claim 2, wherein said abutment surfaces include the end portion of said slide member means forming an inclined cam surface.
 4. A buckle as defined in claim 1, wherein said handle has means forming a guideway for the movement of said push button, said push button having a cantilever extension constituting said portion thereof disposed to engage said slide member cam surface.
 5. A safety belt buckle including a tongue plate adapted to receive a first belt section; a frame; a belt bar movably mounted in said frame between jamming and releasing positions, and adapted to receive and adjustably secure a second belt section; laterally interengageable means on said frame and plate adapted to transfer belt tension forces when said frame and plate means are interengaged; a slide member mounted in said frame for movement in a direction substantially parallel to the axis of belt tension established by the position of said plate and belt bar with said frame and plate means are interengaged, said slide member being movable from locking position maintaining the engagement of said frame and plate means to a position releasing said frame and plate means for lateral separation; and biasing means urging said slide member to locking position, wherein the improvement comprises: a push button mounted in said handle for movement transverse to said axis of belt tension; and means on said slide member forming an inclined cam surface with respect to the direction of movement of said push button, said push button having a portion disposed to engage said cam surface on application of exterior pushing force against said push button, said inclined cam surface being oriented to induce movement of said slide member to release position on actuation of said push button.
 6. A buckle as defined in claim 5, wherein said push button and slide member have interengageable abutment surfaces limiting the travel of said push button.
 7. A buckle as defined in claim 6, wherein said abutment surfaces include the end portion of said slide member means forming an inclined cam surface.
 8. A buckle as defined in claim 5, wherein said handle has means forming a guideway for the movement of said push button, said push button having a cantilever extension constituting said portion thereof disposed to engage said slide member cam surface.
 9. A safety belt buckle including a tongue plate adapted to receive a first belt section; a frame; a belt bar movably mounted in said frame between jamming and releasing positions, and adapted to receive and adjustably secure a second belt section; laterally interengageable means on said frame and plate adapted to transfer belt tension forces when said frame and plate means are interengaged; a slide member mounted in said frame for movement in a direction substantially parallel to the axis of belt tension established by the position of said plate and belt bar with said frame and plate means are interengaged, said slide member being movable from locking position maintaining the engagement of said frame and plate means to a position releasing said frame and plate means for lateral separation; biasing means urging said slide member to locking position; and handle means slideably mounted on said frame for movement in a direction parallel to said axis, said handle having means disposed to intercept said belt bar on movement of said handle in a direction to move said belt bar to release position, said handle also having means disposed to intercept said slide member to induce movement thereof to release position, said latter movement being in the opposite direction to that required to move said belt bar to release position, wherein the improvement comprises: a bush button mounted in said handle for movement transverse to the direction of sliding movement of said handle; means on said slide member forming an inclined cam surface with respect to the direction of movement of said push button, said push button having a portion disposed to engage said cam surface on application of exterior pushing force against said push button, said inclined cam surface being oriented to induce movement of said slide member to release position on actuation of said push button; and means providing resistance of said handle to sliding movement with respect to said frame, said resistance being of a magnitude in excess of the force required to move said slide member to release position.
 10. A buckle as defined in claim 9, wherein said push button and slide member have interengageable abutment surfaces limiting the travel of said push button.
 11. A buckle as defined in claim 10, wherein said abutment surfaces include the end portion of said slide member means forming an inclined cam surface.
 12. A buckle as defined in claim 9, wherein said handle has means forming a guideway for the movement of said push button, said push button having a cantilever extension constituting said portion thereof disposed to engage said slide member cam surface. 